Methods and systems for endovascular aneurysm treatment

ABSTRACT

Aneurysms are treated by filling a double-walled filling structure with a curable medium. The structures may be delivered over balloon deployment mechanisms in order to shape and open tubular lumens therethrough. The filling structures are preferably used in pairs for providing flow into the iliac arteries when treating abdominal aortic aneurysm.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/187,471, filed on Jul. 22, 2005, now issued as U.S. Pat. No.7,530,988 on May 12, 2009, which claims the benefit of prior ProvisionalApplication No. 60/589,850, filed on Jul. 22, 2004, the full disclosuresof which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical apparatus and methodsfor treatment. More particularly, the present invention relates toexpandable prosthesis and methods for treating abdominal and otheraneurysms.

Aneurysms are enlargements or “bulges” in blood vessels which are oftenprone to rupture and which therefore present a serious risk to thepatient. Aneurysms may occur in any blood vessel but are of particularconcern when they occur in the cerebral vasculature or the patient'saorta.

The present invention is particularly concerned with aneurysms occurringin the aorta, particularly those referred to as aortic aneurysms.Abdominal aortic aneurysms (AAA's) are classified based on theirlocation within the aorta as well as their shape and complexity.Aneurysms which are found below the renal arteries are referred to asinfrarenal abdominal aortic aneurysms. Suprarenal abdominal aorticaneurysms occur above the renal arteries, while thoracic aorticaneurysms (TAA's) occur in the ascending, transverse, or descending partof the upper aorta.

Infrarenal aneurysms are the most common, representing about seventypercent (70%) of all aortic aneurysms. Suprarenal aneurysms are lesscommon, representing about 20% of the aortic aneurysms. Thoracic aorticaneurysms are the least common and often the most difficult to treat.Most or all present endovascular systems are also too large (above 12 F)for percutaneous introduction.

The most common form of aneurysm is “fusiform,” where the enlargementextends about the entire aortic circumference. Less commonly, theaneurysms may be characterized by a bulge on one side of the bloodvessel attached at a narrow neck. Thoracic aortic aneurysms are oftendissecting aneurysms caused by hemorrhagic separation in the aorticwall, usually within the medial layer. The most common treatment foreach of these types and forms of aneurysm is open surgical repair. Opensurgical repair is quite successful in patients who are otherwisereasonably healthy and free from significant co-morbidities. Such opensurgical procedures are problematic, however, since access to theabdominal and thoracic aortas is difficult to obtain and because theaorta must be clamped off, placing significant strain on the patient'sheart.

Over the past decade, endoluminal grafts have come into widespread usefor the treatment of aortic aneurysm in patients who cannot undergo opensurgical procedures. In general, endoluminal repairs access the aneurysm“endoluminally” through either or both iliac arteries in the groin. Thegrafts, which typically have been fabric or membrane tubes supported andattached by various stent structures are then implanted, typicallyrequiring several pieces or modules to be assembled in situ. Successfulendoluminal procedures have a much shorter recovery period than opensurgical procedures.

Present endoluminal aortic aneurysm repairs, however, suffer from anumber of limitations. A significant number of endoluminal repairpatients experience leakage at the proximal juncture (attachment pointclosest to the heart) within two years of the initial repair procedure.While such leaks can often be fixed by further endoluminal procedures,the need to have such follow-up treatments significantly increases costand is certainly undesirable for the patient. A less common but moreserious problem has been graft migration. In instances where the graftmigrates or slips from its intended position, open surgical repair isrequired. This is a particular problem since the patients receiving theendoluminal grafts are those who are not considered good candidates foropen surgery. Further shortcomings of the present endoluminal graftsystems relate to both deployment and configuration. The multiplecomponent systems require additional time for introducing each piece andeven more time for assembling the pieces in situ. Such techniques arenot only more time consuming, they are also more technicallychallenging, increasing the risk of failure. Current devices are alsounsuitable for treating many geometrically complex aneurysms,particularly infrarenal aneurysms with little space between the renalarteries and the upper end of the aneurysm, referred to as short-neck orno-neck aneurysms. Aneurysms having torturous geometries, are alsodifficult to treat.

For these reasons, it would desirable to provide improved methods,systems, and prosthesis for the endoluminal treatment of aorticaneurysms. Such improved methods, systems, and treatments shouldpreferably provide implanted prosthesis which result in minimal or noendoleaks, which resist migration, which are relatively easy to deploy,which have a low introduction profile (preferably below 12 F), and whichcan treat most or all aneurismal configurations, including short-neckand no-neck aneurysms as well as those with highly irregular andasymmetric geometries. At least some of these objectives will be met bythe inventions described hereinafter.

2. Description of the Background Art

Grafts and endografts having fillable components are described in U.S.Pat. Nos. 4,641,653; 5,530,528; 5,665,117; and 5,769,882; U.S. PatentPublications 2004/0016997; and PCT Publications WO 00/51522 and WO01/66038.

BRIEF SUMMARY OF THE INVENTION

The present invention provides methods, systems, and prosthesis for theendoluminal treatment of aneurysms, particularly aortic aneurysmsincluding both abdominal aortic aneurysms (AAA's) and thoracic aorticaneurysms (TAA's). The prosthesis comprise double-walled fillingstructures which are pre-shaped and otherwise adapted to substantiallyfill the enlarged volume of an aneurysm, particularly a fusiformaneurysm, leaving a lumen in place for blood flow.

The double-walled filling structures will thus usually have a generallytoroidal structure with an outer wall, an inner wall, a potential spaceor volume between the outer and inner walls to be filled with a fillingmedium, and a generally tubular lumen inside of the inner wall whichprovides the blood flow lumen after the prosthesis has been deployed.The shape of the filling structure will be preferably adapted to conformto the aneurysm being treated. In some instances, the filling structurecan be shaped for the aneurismal geometry of a particular patient usingimaging and computer-aided design and fabrication techniques. In otherinstances, a family or collection of filling structures will bedeveloped having different geometries and sizes so that a treatingphysician may select a specific filling structure to treat a particularpatient based on the size and geometry of that patient's aneurysm. Inall instances, the outer wall of the filling structure will conform orbe conformable to the inner surface of the aneurysm being treated. Whilethe inner wall of the structure will be aligned with lumens of the bloodvessels on either side of the prosthesis after the prosthesis has beendeployed.

The filling structures of the prosthesis will usually be formed from anon-compliant material, such as parylene, Dacron, PET, PTFE, a compliantmaterial, such as silicone, polyurethane, latex, or combinationsthereof. Usually, it will be preferred to form at least the outer wallpartially or entirely from a non-compliant material to enhanceconformance of the outer wall to the inner surface of the aneurysm. Thisis particularly true when the aneurysm has been individually designedand/or sized for the patient being treated.

The walls of the filling structures may consist of a single layer or maycomprise multiple layers which are laminated or otherwise formedtogether. Different layers may comprise different materials, includingboth compliant and/or non-compliant materials. The structure walls mayalso be reinforced in various ways, including braid reinforcementlayers, filament reinforcement layers, and the like. In some instances,it would be possible to include self-expanding scaffolds within thefilling structures so that the structures could be initially deliveredand be allowed to self-expand at the treatment site, thus obviating theneed for an expansion delivery catheter as described as the preferredembodiment below.

Preferred delivery protocols will utilize delivery catheters having aballoon or other expandable support for carrying the filling structure.When using balloons, the balloons will preferably be substantially orentirely compliant, although non-compliant and combinationcompliant/non-compliant balloons may also find use. The balloon or othermechanical expansion components of the delivery catheter will initiallybe disposed within the inner tubular lumen of the filling structure,with the filling structure generally being collapsed into a low width orlow profile configuration over the expansion element. The deliverycatheter may then be introduced intraluminally, typically into the iliacartery and upwardly to the region within the aorta to be treated. Thedelivery catheter will also include one or more lumens, tubes, or othercomponents or structures for delivering the filling medium in a fluidform to an internal filling cavity of the filling structure. Thus, thedelivery catheter can be used to both initially place and locate thefilling structure of the prosthesis at the aneurismal site. Once at theaneurismal site, the internal tubular lumen of the structure can beexpanded using the balloon or other expandable element on the deliverycatheter. The filling structure itself will be filled and expanded bydelivering the filling medium via the catheter into the internal volumeof the filling structure. Both expansion and filling operations may beperformed simultaneously, or can be performed in either order, i.e. thefilling structure may be filled first with the delivery catheter balloonbeing expanded second, or vice versa. The filling structure(s) and/ordelivery balloons may have radiopaque markers to facilitate placementand/or pressure sensors for monitoring filling and inflation pressuresduring deployment.

In preferred aspects of the present invention, the filling structurewill be filled with a fluid (prior to hardening as described hereinbelow) at a pressure which is lower than that of the expansion forceprovided by the delivery catheter, typically the filling pressure of theexpandable balloon. Typically, the filling structure will be filled withfilling medium at a pressure from 80 mm of Hg to 1000 mm of Hg,preferably from 200 mm of Hg to 600 mm of Hg, while the delivery balloonis inflated to a pressure in the range from 100 mm of Hg to 5000 mm ofHg, preferably from 400 mm of Hg to 1000 mm of Hg. These pressures aregage pressures, i.e. measured relative to atmospheric pressure.

As described thus far, in the present invention includes delivery of asingle prosthesis and filling structure to an aneurysm. Delivery of asingle filling structure will be particularly suitable for aneurysmswhich are remote from a vessel bifurcation so that both ends of thefilling structure are in communication with only a single blood vessellumen. In the case of aneurysms located adjacent a vessel bifurcation,such as the most common infrarenal abdominal aortic aneurysms, it willoften be preferable to utilize two such filling structures introduced ina generally adjacent, parallel fashion within the aneurismal volume. Inthe specific case of the infrarenal aneurysms, each prosthesis willusually be delivered separately, one through each of the two iliacarteries. After locating the filling structures of the prosthesis withinthe aneurismal space, they can be filled simultaneously or sequentiallyto fill and occupy the entire aneurismal volume, leaving a pair of bloodflow lumens.

Suitable filling materials will be fluid initially to permit deliverythrough the delivery catheter and will be curable or otherwisehardenable so that, once in place, the filling structure can be given afinal shape which will remain after the delivery catheter is removed.The fillable materials will usually be curable polymers which, aftercuring, will have a fixed shape with a shore hardness typically in therange from 10 durometer to 140 durometer. The polymers may be deliveredas liquids, gels, foams, slurries, or the like. In some instances, thepolymers may be epoxies or other curable two-part systems. In otherinstances, the polymer may comprise a single material which when exposedto the vascular environment within the filling structure changes stateover time, typically from zero to ten minutes.

In a preferred aspect of the present invention, after curing, thefilling material will have a specific gravity, typically in the rangefrom 0.1 to 5, more typically from 0.8 to 1.2 which is generally thesame as blood or thrombus. The filling material may also include bulkingand other agents to modify density, viscosity, mechanicalcharacteristics or the like, including microspheres, fibers, powders,gasses, radiopaque materials, drugs, and the like. Exemplary fillingmaterials include polyurethanes, collagen, polyethylene glycols,microspheres, and the like.

Preferably, the filling structures of the prosthesis will require noadditional sealing or anchoring means for holding them in place withinthe aneurysm. In some instances, however, it may be desirable to employsuch additional sealing or anchoring mechanisms, such as stents,scaffolds, hooks, barbs, sealing cuffs, and the like. For sealing cuffsor stents which extend proximately of infrarenal prosthesis, it may bedesirable to provide openings or ports to allow the anchoring or sealingdevices to extend over the renal ostia while penetrating blood flow intothe renal arteries. The sealing or anchoring devices will typically beattached to and/or overlap with the filling structure of the prosthesisand will provide for a smooth transition from the aortic and/or iliaclumens into the tubular lumens provided by the deployed fillingstructures.

The filling structures may be modified in a variety of other ways withinthe scope of the present invention. For example, the external surfacesof the filling structures may be partially or entirely modified toenhance placement within the aneurismal space, typically by promotingtissue ingrowth or mechanically interlocking with the inner surface ofthe aneurysm. Such surface modifications include surface roughening,surface stippling, surface flocking, fibers disposed over the surface,foam layers disposed over the surface, rings, and the like. It is alsopossible to provide biologically active substances over all or a portionof the external surface of the filling structure, such as thrombogenicsubstances, tissue growth promotants, biological adhesives, and thelike. It would further be possible to provide synthetic adhesives, suchas polyacrylamides, over the surface to enhance adherence.

In some instances, it will be desirable to modify all or a portion ofthe internal surface of the filling cavity of the filling structure.Such surface modifications may comprise surface roughening, rings,stipples, flocking, foam layers, fibers, adhesives, and the like. Thepurpose of such surface modification will usually be to enhance thefilling and bonding to the filling material, and to control the minimumwall thickness when the structure is filled particularly after thefilling material has been cured. In particular instances, in locationsof the filling structure which will be pressed together when thestructure is deployed, thus potentially excluding filling material, itwill be desirable if the surfaces of the filling structure can adheredirectly to each other.

In view of the above general descriptions of the present invention, thefollowing specific embodiments may be better understood. In a firstspecific embodiment, methods for treating an aneurysm comprisepositioning at least one double-walled filling structure across theaneurysm. By “across” the aneurysms, it is meant generally that thefilling structure will extend axially from one anatomical location whichhas been identified by imaging or otherwise as the beginning of theaneurysm to a space-part location (or locations in the case ofbifurcated aneurysm) where it has been established that the aneurysmends. After positioning, the at least one filling structure is filledwith a fluid filling medium so that an out wall of the structureconforms to the inside of the aneurysm and an inner wall of thestructure forms a generally tubular lumen to provide for blood flowafter the filling structure has been deployed. The tubular lumen willpreferably be supported, typically by a balloon or mechanicallyexpansible element, while the filling structure is being filled, afterthe filling structure has been filled, or during both periods. After thefilling structure has been filled, the filling material or medium ishardened while the tubular lumen remains supported. Supporting thetubular lumen during hardening assures that the lumen will have adesired geometry, will properly align with adjacent vascular lumens andthat the tubular lumen being formed remains aligned with the nativeaortic and/or iliac artery lumens after the prosthesis has been fullyimplanted. Preferably, the support will be provided by a balloon whichextends proximally and distally of the filling structure where theballoon may slightly “overexpand” in order to assure the desired smoothtransition and conformance of the tubular lumen provided by the fillingstructure with the native vessel lumens.

After hardening, the support will be removed, leaving the fillingstructure in place. In some instances, however, prior to hardening, itwill be desirable to confirm proper placement of the filling structure.This can be done using imaging techniques or otherwise testing forpatency and continuity. In some instances, it may be desirable to firstfill the filling structure with saline or other non-hardenable substanceto make sure that the geometry of the filling structure is appropriatefor the patient being treated. After testing, the saline may be removedand replaced with the hardenable filler.

In a second specific embodiment of the present invention, abdominalaortic aneurysms and other bifurcated aneurysms are treated bypositioning first and second double-walled filling structures within theaneurismal volume. The first and second double-walled filling structuresare positioned across the aneurysm, as defined above, extending from theaorta beneath the renal arteries to each of the iliac arteries,respectively. The first fluid filling structure is filled with a fluidfilling material, the second filling structure is also filled with afluid material, and the outer walls of each filling structure willconform to the inside surface of the aneurysm as well as to each other,thus providing a pair of tubular lumens for blood flow from the aorta toeach of the iliac arteries. Preferably, the tubular lumens of each ofthe first and second filling structures are supported while they arebeing filled or after they have been filled. Still further preferably,the tubular lumens will remain supported while the filling material ishardened, thus assuring that the transitions to the tubular lumens tothe native vessel lumens remain properly aligned and conformed.

In a third specific embodiment of the present invention, systems fortreating aneurysms comprise at least one double-walled filling structureand at least one delivery catheter having an expandable supportpositionable within a tubular lumen of the filling structure. Thesystems will usually further comprise a suitable hardenable or curablefluid filling medium. The particular characteristics of the fillingstructure and delivery balloon have been described above in connectionwith the methods of the present invention.

In a still further specific embodiment of the present invention, asystem for treating abdominal aortic aneurysms comprises a firstdouble-walled filling structure and a second double-walled fillingstructure. The first and second filling structures are adapted to befilled with a hardenable filling medium while they lie adjacent to eachother within the aneurysm. The systems further comprise first and seconddelivery catheters which can be utilized for aligning each of the firstand second filling structures properly with the right and left iliacsand the infrarenal aorta as they are being deployed, filled, andhardened.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a single prosthesis system comprising a fillingstructure mounted over a delivery catheter.

FIG. 2 is a cross-sectional view of the filling structure of FIG. 1illustrating various surface modifications and a filling valve.

FIGS. 3A-3C illustrate alternative wall structures for the fillingstructure.

FIG. 4 illustrates the anatomy of an infrarenal abdominal aorticaneurysm.

FIGS. 5A-5D illustrate use of the prosthesis system of FIG. 1 fortreating the infrarenal abdominal aortic aneurysm.

FIG. 6 illustrates a system in accordance with the principles of thepresent invention comprising a pair of prosthesis for delivery to aninfrarenal abdominal aortic aneurysm, where each prosthesis comprises afilling structure mounted on a delivery catheter.

FIGS. 7A-7F illustrate use of the prosthesis system of FIG. 6 fortreating an infrarenal abdominal aortic aneurysm.

DETAILED DESCRIPTION OF THE INVENTION

A system 10 constructed in accordance with the principles of the presentinvention for delivering a double-walled filling structure 12 to ananeurysm includes the filling structure and a delivery catheter 14having an expandable element 16, typically an inflatable balloon, at itsdistal end. The catheter 14 will comprise a guidewire lumen 18, aballoon inflation lumen (not illustrated) or other structure forexpanding other expandable components, and a filling tube 20 fordelivering a filling medium or material to an internal space 22 of thedouble-walled filling structure 12. The internal space 22 is definedbetween an outer wall 24 and inner wall 26 of the filling structure.Upon inflation with the filling material or medium, the outer wall willexpand radially outwardly, as shown in broken line, as will the innerwall 26, also shown in broken line. Expansion of the inner wall 26defines an internal lumen 28. The expandable balloon or other structure16 will be expandable to support an inner surface of the lumen 28, asalso in broken line in FIG. 1.

Referring now to FIG. 2, and the various internal and external surfacesmay be shaped, coated, treated, or otherwise modified, to provide for anumber of particular features in accordance with the principles of thepresent invention. For example, the outer wall 24 may be shaped to haverings, stipples, or other surface features which are typically formedinto the material of the structure at the time of molding, vapordeposition, or other manufacturing process. The outer surface may alsobe coated with materials 28 which can be adhesives, drugs, activesubstances, fibers, flocking, foams, or a variety of other materials. Inmost cases, such surface features or modifications will be intended toenhance sealing or attachment of the outer wall 24 to the inner surfaceof the aneurysm being treated.

The inner surface 30 of the filling volume 22 may also be modified byproviding features, coatings, surface roughening, or a variety of othermodifications. The purpose of such internal features is typically toenhance adherence of the walls to the filling material or medium as themedium is cured or otherwise hardened. In some instances, materials maybe coated on all or a portion of the inside surface 30 to induce orcatalyze hardening of the filling material as it is being introduced.

The double-walled filling structure 12 will typically comprise at leastone valve 40 to permit the introduction of the filling material ormedium into the internal volume 22. As illustrated, the valve 40 may bea simple flap valve. Other more complex ball valves, and other one-wayvalve structures may be provided. In other instances, two-way valvestructures may be provided to permit both filling and selective emptyingof the internal volume 22. In other instances, the filling tube maycomprise a needle or other filling structure to pass through the valve40 to permit both filling and removal of filling medium.

As illustrated in FIG. 2, the wall structure of the double-walledfilling structure may be a single layer, typically molded or otherwiseconventionally formed. The wall structures may also be more complex, asillustrated for example, FIGS. 3A-3C. FIG. 3A shows a multi-layered wallcomprising layers 42, 43 and 44. It will be appreciated that suchmultiple layer structure can provide for increased strength, punctureresistance, variations in compliance and/or flexibility, differences inresistance to degradation, and the like. As shown in FIG. 3B, a singlewall or multiple wall structure can be reinforced by braid, coils, orother metal or non-polymeric reinforcement layers or structures. Asshown in FIG. 3C, the external surface 24 of the wall may be coveredwith drugs, fibers, protrusions, holes, active agents or othersubstances for a variety of purposes.

Referring now to FIG. 4, the anatomy of an infrarenal abdominal aorticaneurysm comprises the thoracic aorta (TA) having renal arteries (RA) atits distal end above the iliac arteries (IA). The abdominal aorticaneurysm (AAA) typically forms between the renal arteries (RA) and theiliac arteries (IA) and may have regions of mural thrombus (T) overportions of its inner surface (S).

Referring to FIGS. 5A-5D, the treatment system 10 of FIG. 1 may beutilized to treat the complex geometry of the transmural abdominalaortic aneurysm (AAA) of FIG. 4 by first positioning the deliverycatheter 14 to place the double-walled filling structure 12 (in itsunfilled configuration) generally across the aneurysm from the region ofthe aorta beneath the renal arteries (RA) to a region over the iliacarteries (IA), as best seen FIG. 5A. Usually, the delivery catheter 14will be introduced over a guidewire, (GW) through a puncture in thepatient's groin accessing the iliac artery by the Seldinger technique.

After the double-walled filling structure 12 is properly positioned, ahardenable inflation medium is introduced into the internal space 22filling of the inner space 22 expands the outer wall 24 of the structureoutwardly so that it conforms to the inner surface (S) of the aneurismalspace.

Before, during, or after filling of the double-walled filling structure12 with inflation medium, as illustrated in FIG. 5B, the balloon 16 orother expansible structure will also be inflated or expanded to open thetubular lumen defined by the interior of the inner wall 26. In apreferred embodiment, the balloon 16 will be generally non-compliant,typically having a maximum diameter of width which is at or slightlylarger than the desired tubular lumen diameter or width through thedeployed filling structure 12. The filling structure 12, in contrast,will be partially or completely formed from a generally compliantmaterial, thus allowing the non-compliant balloon or other expansiblestructure 16 to fully open the tubular lumen and conform the ends of thelumens to the aorta and iliac walls, as illustrated in FIG. 5C. A loweror proximal end 50 of the tubular lumen will be flared to a largerdiameter so that it can accommodate the openings into both of the iliacarteries (IA) as illustrated. Thus, it will be preferred to utilize afilling structure 12 geometry which has been chosen or fabricated tomatch the particular patient geometry being treated. It will also bepreferable to use a balloon 16 or other expansible structure which willbe shaped to preferentially open the lower proximal end 50 of thetubular lumen to a larger diameter than the upper or distal end 52.

After the filling material has been introduced to the filling structure12, typically through the filling tube 20, the fluid filling materialmust be cured or otherwise hardened to provide for the permanent implanthaving a generally fixed structure which will remain in place in theparticular aneurismal geometry. Methods for curing or hardening thefilling material will depend on the nature of the filling material. Forexample, certain polymers may be cured by the application of energy,such as heat energy or ultraviolet light. Other polymers may be curedwhen exposed to body temperature, oxygen, or other conditions whichcause polymerization of the fluid filling material. Still others may bemixed immediately prior to use and simply cure after a fixed time,typically minutes. Often, after the filling material has been hardened,the delivery catheter 12 may be removed and the filling structure leftin place as the completed prosthetic implant.

In other cases, however, it may be desirable to further position certainseals, anchors, stents, or other additional prosthetic components ateither the proximal end 52 or distal end 50 of the graft. As illustratedin FIG. 5D, for example, a stent-like structure may be planted in theupper proximal opening 52 of the tubular lumen of the filling structure12 in order to help anchor the structure, help prevent intrusion ofblood into the region between the outer wall 24 and inner surface (S) ofthe aneurysm, and to generally improve the transition from the aortainto the tubular lumen. The sealing or anchoring structure may simplycomprise a stent-like component, preferably having a port or otheraccess route to allow blood flow into the covered renal arteries (ifany). Alternatively, the anchor structure could be another inflatableunit, such as the anchor described in co-pending, commonly ownedapplication Ser. No. 10/668,901 (published as US2004/0116997A1), thefull disclosure of which is incorporated herein by reference.

In a particular and preferred aspect of the present invention, a pair ofdouble-walled filling structures will be used to treat infrarenalabdominal aortic aneurysms, instead of only a single filling structureas illustrated in FIGS. 5A-5C. A system comprising such a pair offilling structures is illustrated in FIG. 6 which includes a firstfilling structure 112 and a second filling structure 212. Each of thefilling structures 112 and 212 are mounted on delivery catheters 114 and214, respectively. The components of the filling structures 112 and 212and delivery catheters 114 and 214 are generally the same as thosedescribed previously with respect to the single filling structure system10 of FIG. 1. Corresponding parts of each of the fillings systems 112and 212 will be given identical numbers with either the 100 base numberor 200 base number. A principal difference between the fillingstructures 112 and 212, on the one hand, and the filling structure 12 ofFIG. 1 is that the pair of filling structures will generally haveasymmetric configurations which are meant to be positioned adjacent toeach other within the aneurismal space and to in combination fill thatspace, as will be described with specific reference to FIG. 7A-7F below.

In treating an infrarenal abdominal aortic aneurysm using the pair offilling structures 112 and 212 illustrated in FIG. 6, a pair ofguidewires (GW) will first be introduced, one from each of the iliacarteries (IA). As illustrated in FIG. 7A. The first delivery catheter114 will then be positioned over one of the guidewires to position thedouble-walled filling structure 112 across the aortic aneurysm (AAA), asillustrated in FIG. 7B. The second delivery catheter 214 is thendelivered over the other guidewire (GW) to position the second fillingstructure 212 adjacent to the first structure 112 within the aneurysm(AAA), as illustrated in FIG. 7C. Typically, one of the fillingstructures and associated balloons will be expanded first, followed bythe other of the filling structures and balloon, as illustrated in FIG.7D where the filling structure 112 and balloon 116 are inflated to fillgenerally half of the aneurismal volume, as illustrated in FIG. 7D.Filling can generally be carried out as described above with the onefilling structure embodiment, except of course that the fillingstructure 112 will be expanded to occupy only about one-half of theaneurismal volume. After the first filling structure 112 has beenfilled, the second filling structure 212 may be filled, as illustratedin FIG. 7E. The upper ends of the balloons 116 and 216 will conform thetubular lumens of the filling structures against the walls of the aortaas well as against each other, while the lower ends of the balloons 116and 216 will conform the tubular lumens into the respective iliac (IA).

After filling the filling structures 112 and 212 as illustrated in FIG.7E, the filling materials or medium will be cured or otherwise hardened,and the delivery catheters 114 and 214 removed, respectively. Thehardened filling structures will then provide a pair of tubular lumensopening from the aorta beneath the beneath the renal arteries to theright and left iliac arteries, as shown in broken line in FIG. 7. Theability of the filling structures 112 and 212 to conform to the innersurface (S) of the aneurysm, as shown in FIG. 7F, helps assure that thestructures will remain immobilized within the aneurysm with little or nomigration. Immobilization of the filling structures 112 and 114 may befurther enhanced by providing any of the surface features describedabove in connection with the embodiments of FIG. 2. Optionally, and notillustrated, anchoring or sealing structures could be provided in eitherof the upper or proximal openings of the tubular lumens into the aortaor from either of the distal or lower openings into the respective iliacarteries.

1. A method for treating an aneurysm, said method comprising:positioning a first double-walled filling structure across the aneurysm,the filling structure having an inner wall and an outer wall;positioning a second double-walled filling structure across theaneurysm, the filling structure having an inner wall and an outer wall,wherein the second filling structure is separate and distinct from thefirst filling structure and positioned adjacent the first fillingstructure; filling the first filling structure with a first fluidfilling medium so that the outer wall conforms to the inside of theaneurysm; removing the first fluid filling medium from the first fillingstructure; filling the first filling structure with a second fluidfilling medium so that the outer wall conforms to the inside of theaneurysm and the inner wall forms a first generally tubular lumen toprovide for blood flow to a first iliac artery, wherein the fillingstructure is filled at a first filling pressure; filling the secondfilling structure with the first fluid filling medium so that the outerwall conforms to the inside of the aneurysm; removing the first fluidfilling medium from the second filling structure; filling the secondfilling structure with the second fluid filling medium so that the outerwall conforms to the inside of the aneurysm so that, in combination, thefirst and second filling structure fills the aneurysmal space, and theinner wall of the second filling structure forms a second generallytubular lumen to provide for blood flow to a second iliac artery,wherein the filling structure is filled at a second filling pressure;expanding a first tubular support in the aneurysm to a first inflationpressure, wherein the inflation pressure is greater than the firstfilling pressure while the first filling structure is being filled;expanding a second tubular support in the aneurysm to a second inflationpressure, wherein the inflation pressure is greater than the secondfilling pressure while the second filling structure is being filled;supporting the entire inner wall of the first and second tubular lumenswith the first and second expanded tubular support, respectively, whileand after the first and second filling structures are being filled withthe second fluid filling medium, wherein the expanded tubular supportsdefine the shape of the respective generally tubular lumen; allowinghardening of the second fluid filling medium disposed in the firstfilling structure while the first tubular lumen remains supported;removing the first tubular support from the first tubular lumen afterthe second fluid filling medium in the first filling structure hashardened; allowing hardening of the second fluid filling medium disposedin the second filling structure while the second tubular lumen remainssupported; and removing the second tubular support from the secondtubular lumen after the second fluid filling medium in the secondfilling structure has hardened.
 2. A method as in claim 1, wherein thefirst and second filling pressures are in the range from 100 mm Hg to1000 mm Hg and the first and second inflation pressures are in the rangefrom 200 mm Hg to 5000 mm Hg.
 3. A method as in claim 1, wherein thefirst fluid filling medium comprises saline.
 4. A method as in claim 1,wherein the second fluid filling medium comprises a flowable polymerwhich is curable in situ.
 5. A method as in claim 1, further comprisingmonitoring the filling pressure of the first and second fillingstructure.
 6. A method as in claim 1, further comprising monitoring theinflation pressure of the first and second tubular support.
 7. A methodas in claim 1, wherein at least one of the first and second tubularsupports comprises an inflatable balloon.
 8. A method as in claim 1,wherein at least one of the first and second tubular supports comprisesa mechanical structure expandable to one or more fixed diameters.
 9. Amethod for treating an aneurysm, said method comprising: positioning afirst double-walled filling structure across the aneurysm, the fillingstructure having an inner wall and an outer wall; positioning a seconddouble-walled filling structure across the aneurysm, the fillingstructure having an inner wall and an outer wall, wherein the secondfilling structure is separate and distinct from the first fillingstructure and positioned adjacent the first filling structure; fillingthe first filling structure with a first fluid filling medium at a firstfilling pressure so that the outer wall conforms to the inside of theaneurysm and the inner wall forms a first generally tubular lumen toprovide for blood flow to a first iliac artery; removing the first fluidfilling medium from the first filling structure; filling the firstfilling structure with a second fluid filling medium at a second fillingpressure so that the outer wall conforms to the inside of the aneurysmand the inner wall forms the first generally tubular lumen to providefor blood flow to the first iliac artery; filling the second fillingstructure with a third fluid filling medium at a third filling pressureso that the outer wall conforms to the inside of the aneurysm and theinner wall forms a second generally tubular lumen to provide for bloodflow to a second iliac artery; removing the third fluid filling mediumfrom the second filling structure; filling the second filling structurewith a fourth fluid filling medium at a fourth filling pressure so thatthe outer wall conforms to the inside of the aneurysm and the inner wallforms the second generally tubular lumen to provide for blood flow tothe second iliac artery; expanding a first tubular support in theaneurysm to a first inflation pressure, wherein the inflation pressureis greater than the first and the second filling pressures while thefirst filling structure is being filled; supporting the entire innerwall of the first tubular lumen with the expanded first tubular supportwhile and after the first filling structure is being filled with thesecond fluid filling medium, wherein the expanded first tubular supportdefines the shape of the first lumen; allowing hardening of the secondfluid filling medium disposed in the first filling structure while thefirst tubular lumen remains supported by the first expanded tubularsupport; removing the first tubular support from the first tubular lumenafter the second fluid filling medium in the first filling structure hashardened; expanding a second tubular support in the aneurysm to a secondinflation pressure, wherein the inflation pressure is greater than thethird and fourth filling pressures while the second filling structure isbeing filled; supporting the entire inner wall of the second tubularlumen with the expanded second tubular support while and after thesecond filling structure is being filled with the fourth fluid fillingmedium, wherein the expanded second tubular support defines the shape ofthe second lumen; allowing hardening of the fourth fluid filling mediumdisposed in the second filling structure while the second tubular lumenremains supported by the second expanded tubular support; and removingthe second tubular support from the second tubular lumen after thefourth fluid filling medium in the second filling structure hashardened.
 10. A method as in claim 9, wherein the filling pressures arein the range from 100 mm Hg to 1000 mm Hg and the inflation pressuresare in the range from 200 mm Hg to 5000 mm Hg.
 11. A method as in claim9, wherein the step of filling the first filling structure with a firstfluid filling medium comprises measuring the volume of the first fluidfilling medium required to fill the first filling structure to the firstpressure, and the steps of filling the first filling structure with thesecond fluid filling medium comprises filling the first fillingstructure with substantially the same volume of the second fluid fillingmedium.
 12. A method as in claim 9, wherein the first and third fluidfilling medium comprise saline.
 13. A method as in claim 9, wherein thesecond and fourth fluid filling medium comprise a flowable polymer whichis curable in situ.
 14. A method as in claim 9, wherein at least one ofthe first and second tubular supports comprises an inflatable balloon.15. A method as in claim 9, wherein at least one of the first and secondtubular lumen supports comprises a mechanical structure expandable toone or more fixed diameters.
 16. A method as in claim 9 for treating ananeurysm, said method further comprising: filling the first fillingstructure with a fifth fluid filling medium so that the outer wallconforms to the inside of the aneurysm before filling with the firstfluid filling medium.
 17. A method as in claim 16, said method furthercomprising: filling the second filling structure with a sixth fluidfilling medium so that the outer wall conforms to the inside of theaneurysm before filling with the third fluid filling medium.
 18. Amethod as in claim 16, wherein the at least one of the fifth and sixthfluid filling medium comprises saline.
 19. A method as in claim 9wherein each of the first and second filling structures has anasymmetric configuration such that when placed adjacent to each other,the first and second filling structures fill the aneurysmal space whenfilled.
 20. A method as in claim 9 wherein the first and second fillingstructure are filled simultaneously.
 21. A method as in claim 9 whereinthe first and second filling structures are filled sequentially.